A couple of years after Luna returns from her banishment, she tries to find that lost sibling-ship she previously had with her sister, Princess Celestia. When Celestia finds some time off, Luna can't wait to spend time with her only sister. That is, until Tia falls ill and needs to spend her break to recover. Heartbroken, Luna finds an alternative: cloning. It is successful in every way but in two: first, there is four, not one. And two, instead of being just like the original, they exemplify a past and personal trouble the real princess has hid from the public and Luna. With the fakes running off, Luna, Discord, and Twilight need to find and put them back before the real princess is gone forever.